It is well known in the art that sharp toothed wire or the like is used in many areas of carding and spinning and related textile operations. In open-end spinning, for example, a sliver of separate fibers is fed into a combing roller which is provided with metallic wires having saw teeth wound around the periphery of the roller. The wires contact the fibers and comb them. From the combing roller, the fibers are then transferred to a rotor where the combed fibers are twisted to form a yarn which is then transferred to a take-up spool. Examples of combing rollers and various toothed combing wires associated therewith can be found with reference to U.S. Pat. Nos. 2,937,413; 4,233,711; 2,731,676; 4,435,953; and 3,833,968 which are incorporated herein by reference. An alternative device to the combing roller is a pin-ring which functions in the same way but employs a multiplicity of pins extending from the roller (sleeve) rather than the toothed surface. For the purpose of this invention, the terms combing rolls, carding rolls, pin-rings, and beater rolls (or rollers) are used interchangeably.
These rollers are currently driven at speeds of 5,000-10,000 RPM (as described in U.S. Pat. No. 4,435,953) with higher speeds expected in the future which cause tooth wear with time, and thus reduce the efficiency of the entire operation by lowering the quality of the product produced over time and lowering the general efficiency of the combing process causing knots and neps in the yarn produced, and causing yarn breaks which cause the individual spinning position to shut down, or produce defective yarn.
The general make-up of the wire (or pins, in the case of pin ring beater rolls) containing the teeth that do the fiber combing is made up of two different parts: the base of the wire, and the toothed portion of the wire. This wire is generally made from steel. Methods of manufacture and final wire or tooth specifications vary with manufacturer, but common practice for its manufacture is starting with a wire having an initially round section, such section being modified by a process of roll to give a wire which is finally strip-like with a rib running along one side to constitute a base or foundation for the finished strip (as described in U.S. Pat. No. 2,731,676). This base portion is then imbedded in the comber roller, be it a solid piece or a sleeve after suitable treatment to make the wire metallurgically suitable in terms of hardness, ductility, and hopefully wear resistance.
One commonly used method for the formation of the toothed portion itself is a punching operation which imparts the shape of the tooth along with the proper angles for the most efficient carding and combing of a specific type of fiber.
After punching, another mechanical process (described in U.S. Pat. No. 4,233,711) which is used is a grinding operation. This grinding operation has the primary function of imparting an exact evenness to the teeth, making them all exactly uniform, as well as removing any unwanted defects from the punching operation. Also as a final step, some manufacturers post-treat this wire using "needle finishing" which imparts a smoothness to the sides of the teeth, along with a very light or small amount of directional lines in the steel tooth which run approximately parallel to the base portion of the wire. This also helps the efficiency of the combing operation which reduces undesired "loading" of the teeth.
With use, the degradation of the tooth geometry occurs, namely the dulling of the tip of the tooth and the dulling of the leading tooth edges along with an eventual general wearing of the entire tooth portion of the wire. In order to prevent excessive wear, or slow down the wearing process, many coatings or wire treatments have been devised and attempted, as can be seen in the following methods and patents: heat treatment of carbonitriding, surface hardening by carbonitriding, or electrospark coating including vanadium carbide, chromium carbide, tungsten carbide, titanium carbide, zirconium carbide, hafnium carbide, and iron boride, which are applied by the diffusion treatment process. In still another process a chromium layer is electrodeposited onto the teeth of the combing roll, imparting a hard chromium wear resistant layer over the steel tooth (as described in U.S. Pat. No. 4,169,019).
A more popular and seemingly more wide-spread method of protecting the combing teeth is by the electroless deposition of a "composite" coating. The composite coatings usually are comprised of small, wear resistant particles which are co-deposited with an electroless metal matrix (usually, but not limited to, the nickel-phosphorous type matrix). The wear resistant particles can range from aluminum oxides and silicon carbides, to natural and synthetic diamonds, both polycrystalline and/or monocrystalline in nature, as well as lubricating particles. These coatings and the like may be applied according to the technology taught in U.S. Pat. Nos. 3,940,512; 4,358,923; 4,547,407; 4,419,390; and U.S. Reissue Pat. No. 29,285, which patents are incorporated herein by reference. Review of this technology is made in Metal Finishing, August (1983) p. 35.
It is desireable that these electroless and electroless composite coatings be as smooth and uniform as possible. However, it has been observed that on many occasions small auxiliary matter containing the electroless metal in the shape of balls, or microspheres, form on the teeth which lead to a condition which may cause damage to the yarn to be processed along with the combing roll and excess dusting. I have now discovered a solution for this problem. It may be noted that though the problem and solution is described herein in terms of a combing roller, the problem and the solution set forth herein are equally applicable to the electroless plating of any ferromagnetic material with nickel or cobalt or other electrolessly deposited metal and particularly with a composite nickel or cobalt coating.